Function pipe

src/licensedcode/_vendor/attr/_make.py:3120–3173

A converter that composes multiple converters into one. When called on a value, it runs all wrapped converters, returning the *last* value. Type annotations will be inferred from the wrapped converters', if they have any. :param callables converters: Arbitrary number of c

(*converters)

def pipe(*converters):
    """
    A converter that composes multiple converters into one.

    When called on a value, it runs all wrapped converters, returning the
    *last* value.

    Type annotations will be inferred from the wrapped converters', if
    they have any.

    :param callables converters: Arbitrary number of converters.

    .. versionadded:: 20.1.0
    """

    def pipe_converter(val):
        for converter in converters:
            val = converter(val)

        return val

    if not PY2:
        if not converters:
            # If the converter list is empty, pipe_converter is the identity.
            A = typing.TypeVar("A")
            pipe_converter.__annotations__ = {"val": A, "return": A}
        else:
            # Get parameter type.
            sig = None
            try:
                sig = inspect.signature(converters[0])
            except (ValueError, TypeError):  # inspect failed
                pass
            if sig:
                params = list(sig.parameters.values())
                if (
                    params
                    and params[0].annotation is not inspect.Parameter.empty
                ):
                    pipe_converter.__annotations__["val"] = params[
                        0
                    ].annotation
            # Get return type.
            sig = None
            try:
                sig = inspect.signature(converters[-1])
            except (ValueError, TypeError):  # inspect failed
                pass
            if sig and sig.return_annotation is not inspect.Signature().empty:
                pipe_converter.__annotations__[
                    "return"
                ] = sig.return_annotation

    return pipe_converter